A trap in the Three Knights Game

After 1.e4 e5 2.Nf3 Nc6, White's 3.Nc3 invites Black to play the Four Knights Game with 3...Nf6. If Black doesn't want to do that, 3...g6 is an alternative. But Black has to be vigilant after 4.d4 exd4 5.Nd5!? Bg7 6.Bg5! Correct is the counterintuitive 6...Nce7!, when Black will drive back White's pieces with ...c6 and ...h6. For a famous example where this strategy succeeded, see Gufeld-Petrosian, USSR (ch) 1969. The natural 6...Nge7? on the other hand (see diagram), is a bad mistake. After 7.Nxd4!, Black is in big trouble. Black drops the queen after 7...Nxd4? 8.Bxe7. Best is 7...f6!, when Black loses a pawn but can play on. What happens after 7...Bxd4?? Black found out in the following game.